Glutamic acid is a neurotransmitter which mediates an excitatory transmittance in a central nervous system. In addition to various neurotransmitting actions, glutamic acid participates in many important brain functions such as existence and death as well as differentiation and proliferation of nerve cells, development and maturation of nerve and glia cells and plastic change of neurotransmitting efficiency of developed brain (refer, for example, to Annual Review of Biophysics and Biomolecular Structure, volume 23, page 319 (1994)).
According to pharmacological and molecular biological studies, glutamic acid receptors in central nervous system of mammals are classified into two groups which are glutamic acid receptor of an ion channel type and metabotropic glutamic acid receptor (hereinafter, it will be referred to as “mGluR”). Glutamic acid receptor of an ion channel type comprises a complex of different subunit proteins and is an ion channel which is opened and closed by binding of ligand. On the other hand, mGluR is conjugated to GTP-binding protein and shows an action by regulating the activity of ion channel or the production of intracellular second messenger via GTP-binding protein (refer, for example, to Brain Research Reviews, volume 26, page 230 (1998)).
According to the result of studies up to now, mGluR has been reported to be present as eight different kinds of subtypes of mGluR1 to 8. They are classified into three subgroups depending upon homology of amino acid sequence, signal transmission and pharmacological characteristics. With regard to intracellular signal transmission, the group I (mGluR1 and 5) activates phospholipase C and the group II (mGluR2 and 3) and the group III (mGluR 4, 6, 7 and 8) regulate the adenylate cyclase activity whereby they suppress the accumulation of cyclic adenosine monophosphate (cAMP) by stimulation with forskolin. The group II is also selectively activated by LY 354740 mentioned, for example, in Journal of Medicinal Chemistry, volume 42, page 1027 (1999) while the group III is selectively activated by L-AP4. Further, various kinds of receptors are expressed in a broad range of cerebral and nervous system except mGluR6 specifically existing in the retina and, moreover, each of them shows a characteristic distribution in the brain whereby each receptor has been believed to play different physiological role (refer, for example, to Neurochemistry International, volume 24, page 439 (1994) and European Journal of Pharmacology, volume 375, page 277 (1999)).
With regard to a compound which is similar to the compound concerning the present invention, a compound represented, for example, by the formula (A) is mentioned (refer to Patent Document 1).

The use of the compounds concerning the invention mentioned in Patent Document 1 is treatment and prevention of schizophrenia and Parkinson's disease but the compound represented by the above-mentioned formula (A) is an intermediate for the production of the compounds concerning the invention mentioned in Patent Document 1 and there is neither description nor suggestion therein that the compound represented by the formula (A) is useful as treatment and prevention for any disease.